Iraq's prime minister will seek U.S. President Barack Obama's help to acquire billions of dollars in drones and other U.S. arms to fight the Islamic State group during a U.S. visit next week, a senior Iraqi official told Reuters.

Facing a cash crunch due to a plunge in oil prices and a budget deficit of roughly $21 billion this year, Prime Minister Haidar al-Abadi wants to defer payment for the purchases, said the official who spoke on condition of anonymity.

Abadi is grappling with an insurgency by militants from Islamic State, an al-Qaida offshoot that emerged from the chaos in Iraq and neighboring Syria and seized much of northern and central Iraq last year.

Visiting Washington for the first time as prime minister, he hopes to convince a war-weary United States Iraq deserves more U.S. manpower and arms three years after U.S. troops withdrew from the country in December 2011, as his fledgling army confronts the Islamic State group, also known as ISIS and ISIL.

'Everybody's problem'

"ISIS is everybody's problem now," said the Iraqi official. "You can't run away from the problem if it comes to Canada or goes to France," he said in reference to attacks by people influenced by Islamic State or al-Qaida in those countries.

The official hinted Baghdad could turn to Tehran if it did not get the aid it wants from Washington.

"If that's not available, we've already done it with the Iranians and others," he said, saying that was not the first choice. "The PM is committed to the U.S. ... What he also wants to make sure is that he has a partner that he can rely on."

Obama in August authorized the first U.S. airstrikes on Iraq since the U.S. withdrawal and has deployed about 3,000 American military forces to help Iraq to battle the group. But he has also imposed limits on the U.S. military role on the ground to training and advising Iraqi and Kurdish forces.

The official said Abadi, who is to meet Obama on Tuesday, wanted to explore obtaining a series of advanced weapons, including unarmed drone aircraft, Apache attack helicopters manufactured by Boeing Co. and ammunition. He will also seek permission to postpone payment for the weaponry.

"We're talking about billions here," the official said. "This is a new approach for us because of the scale of the challenge we have ahead. Mosul and Nineveh province and Anbar will cost us a lot."

National Security Council spokesman Alistair Baskey said the United States will continue to consult Iraq's leaders to ensure they have what they need to fight Islamic State.

"The United States is committed to providing essential equipment to Iraqi security forces, including Kurdish forces, as part of the Coalition fight against ISIL," he said.

Meeting between officials

U.S. Defense Secretary Ash Carter told reporters on a visit to Hawaii he expected to meet Abadi in Washington.

Asked whether the United States would consider providing equipment including Apache helicopters on deferred payment, he replied, "We will consider any request he makes we have been conducting all of our support to the counter-ISIL campaign in Iraq through the Iraqi government and that's the way we want to keep doing it."

Aware of the time it takes to train pilots, one possibility that could also be explored during Abadi's visit would be the United States loaning Apaches to Iraq, along with the pilots to fly them. Likely payment terms on those and the other arrangements for U.S. arms were unclear.

The Iraqi government on April 2 claimed victory over Islamic State insurgents in Tikrit after a month-long battle for the city supported by Shi'ite militiamen and U.S.-led air strikes, an achievement marred by complaints of militia looting and burning of homes in the Sunni city.

Seeking to gain momentum, Iraqi security forces on Wednesday launched a new offensive against Islamic State in the Sunni Muslim heartland of Anbar. They are eventually expected to move on to Nineveh and its capital Mosul, the group's stronghold.

But Iraq is still burdened by a legacy of sectarianism. Its minority Sunni population resented former Prime Minister Nouri al-Maliki's Shi'ite-majority government and were incensed by his ordering troops to clear a Ramadi protest camp in December 2013.

U.S. officials believe they have a better partner in Abadi but are still wary of the volatile politics in a fractured country that is seeing Iran strengthening its role.